<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        .header {
            width: 100%;
            height: 100px;
            background-color: pink;
        }

        .body {
            width: 80%;
            height: 700px;
            background-color: skyblue;
            margin: 10px auto;
        }

        .body .banner {
            width: 100%;
            height: 20%;
            background-color: #f0f;
        }
        .body .second {
            width: 100%;
            height: 100%;
        }

        .body .second>div {
            float: left;
            width: 24%;
            height: 200px;
            background-color: #ff0;
            margin-right: 15px;
            margin-top: 20px;
        }

        .body .three>div {
            float: left;
            width: 24%;
            height: 300px;
            background-color: #f00;
            margin-right: 15px;
            margin-top: 20px;
        }

        .footer {
            width: 100%;
            height: 100px;
            background-color: #0ff;
        }
    </style>
</head>

<body>
    <div class="header">header</div>
    <div class="body">
        <div class="banner">banner</div>
        <div class="second">
            <div>1</div>
            <div>2</div>
            <div>3</div>
            <div>4</div>
        </div>
        <div class="three">
            <div>1</div>
            <div>2</div>
            <div>3</div>
            <div>4</div>
        </div>
    </div>
    <div class="footer">footer</div>
</body>

</html>